Oxford County is upgrading one of the lagoon cells at the Tavistock Wastewater Treatment Plant (WWTP). Regular maintenance is needed to ensure the lagoon system is operating efficiently and protects the local ecosystem.
What we’ve done since our last update
In response to community feedback about odour, we paused construction in the spring to look for additional measures we could take to address this concern.
- We temporarily returned Cell 1 to its normal operating capacity to manage odours to the degree possible. We used Bioxide (calcium nitrate) and hydrogen peroxide to more quickly restore the natural microbial biological action that is needed in the lagoon cell to most effectively break down sewage.
- In July, we expanded our odour control system to include a new vapour pipeline system along the lagoon property line that blows a dry mist odour neutralizer through pipelines and into the air to bind with odourous materials. This expanded system is intended to provide a more effective and longer lasting odor neutralizer that can cover a wider area around the lagoon cells.
- All sewage flows to the Tavistock WWTP are now being diverted into Cell 2. We have relocated surface aerators from Lagoon Cell 1 to Cell 2 to boost performance of this cell to prepare to restart construction on Cell 1. We’ve also set up an automated dosing system for Bioxide for Cell 2 to enhance its biological performance (and odour management capacity) during peak times.
- We have left extra aeration time for sewage to break down in Lagoon Cell 1 before resuming construction.
Managing odour as we restart construction
Later this month, we will begin transferring treated sewage in Lagoon Cell 1 into Lagoon Cell 2. Once Cell 1 is emptied, active work can then begin to dry and remove the remaining biosolids over the latter part of the summer and early fall. The biosolids will need some time to naturally dry out and odours can be present when biosolids are first exposed to air.
In addition to the expanded vapour pipeline system, we are using chemical treatment enhancers to boost operational performance of the lagoon (Bioxide additions to Cell 2) to manage odour to the degree possible. We have also made preparations to apply thickening agents or other materials directly to the biosolids to help speed up the drying process as appropriate. We are also exploring other processes for removing biosolids that may allow a shorter drying time so that we can move them offsite sooner.
Oxford County is committed to the health and safety of residents and the environment. As we have explained, all operational practices during construction were reviewed by the Ministry of the Environment, Conservation and Parks before undertaking these essential capital upgrades, which are required to ensure the lagoon’s continued safe and effective operation.
We thank the community for its patience as we continue our work at the Tavistock WWTP while working to address your concerns. For more information on this project:
Visit our project information page at www.oxfordcounty.ca/speakup
Jesse Keith, P.Eng., Project Engineer
1-866-537-7778, ext. 3194
Alex Brown, C. Tech, Construction Coordinator
1-866-537-7778, ext. 3138
(For map with Cell 1 Vapour System Location see attached PDF file)